Blowpipe



Patented Jan. 15, 1935 UNITED STATES PATENT OFFICE 1 Claim.

My invention relates particularly to that type of blowpipe that iscommonly employed by practitioners of the dental profession and bychemists, jewelers, etc., and is especially directed to blowpipes thatare designed to produce a fine needlelike flame and to burn illuminatinggas of high calorific content intensified by a jet of pressure forcedair.

Blowpipes as heretofore constructed failed to satisfactorily produce thedesired slender needlelike flame as required in the fabrication oforthodontic appliances when employed to burn gases of high calorificcontent, such as natural gases.

The principal objects of my invention are to provide a blowpipe soconstructed and proportioned that it may be employed to use eitherartificial or natural gases with substantially equal facility, and toproduce a long slender needlelike flame of maximum heat efficiency.

Other objects of my invention are to provide.

a blowpipe in which the outlet orifice of the air nozzle is so relatedto the restricted outlet orifice of the gas nozzle that air is emittedtherefrom directly into the condensed or constricted area of the streamof gas of high calorific content as it emerges from said restrictedoutlet orifice.

Specifically stated, the form of my invention as hereinafter describedcomprises a hollow body adjustably supported and having air and gasinlets and a nozzle provided with a restricted gas outlet orifice, anair tube connected with the air inlet and terminating in a tubularcylindriform extension of minimum diameter projecting through saidnozzle and its orifice to a point slightly beyond the end of saidnozzle.

My invention also includes all of the various novel features ofconstruction and arrangement as hereinafter more definitely specified.

In the accompanying drawing, Figure 1 is a perspective view showing acommon form of blowpipe of the type contemplated and convenientlyembodying my invention; Fig. 2 is a central vertical sectional view ofthe blowpipe shown in Fig. 1, and taken transverse to the plane of theaxes of the inlets; Fig. 3 is an enlarged transverse vertical sectionalview of the blowpipe proper without the base or stand upon which it issupported, the section being taken in the plane of the axes of theinlet; Fig. 4 is a plan sectional view taken through the gas inlet onthe line 4-4 in Fig. 3; and Fig. 5 is a plan sectional view takenthrough the air inlet on the line 5-5 in Fig. 3.

In said figures, the blowpipe comprises the hollow body 1 having thethreaded boss 2 at its upper end and being bifurcated at its lower endto form the lugs 3, and provided with the bore 5 having the screwthreads 6, and the counterbore '7 extending through said boss.

The body 1 is provided with the tubular nipples 9 and 10 respectivelyarranged to be connected by flexible tubing, not shown, with suitablesources of air and gas, the nipple 9 being connected with the bore 2 andthe nipple 10 being connected with the counterbore '7.

A hollow cylindrical gas nozzle 12 is adjustably connected in threadedengagement with the boss 2, and forms the gas chamber 13, the transverseend wall 15 of which has the restricted gas outlet orifice l6.

Said transverse end wall 15 has a substantially flat outer surface,while its inner surface is substantially conical and so formed as tocause gas emitted from the chamber 13 under pressure to assume a conicalfilm formation in which the angle of the conical walls is obtuse.

Air is directed from the bore 5 through the air nozzle comprising thetubular conveyer 17 which extends through the counterbore 7, beingconnected at its inner end in threaded engagement with the threads 6 ofsaid bore 5, and being provided at its outer end with the extensioncomprising the tube 19 of minimum diameter, which extends through thegas chamber 13 and outlet orifice 16, and projects slightly beyond theouter end of the gas nozzle 12 and terminates at the apex of saidconical film of gas.

As shown in Figs. 1 and 2, the body 1 is adjustably supported on thebase 20, having the upwardly projecting lugs 21, which are pivotallyconnected by the links 22 and 23 with the lugs 3 on said body 1, saidlinks being connected together by the screw pintal 25 and respectivelyconnected by the pintals 26 and 2'7 with the lugs 21 and 3.

It may be here noted that the amount of projection of the air conveyingtube 19 beyond the end of the nozzle 12, as well as the relativeproportions of the cooperative parts of the blowpipe, are vital to itssatisfactory performance in producing a slender needle flame from themixture of natural gas and pressure forced air.

It will be obvious that the relative distance between the end of the gasnozzle 12' and the projected end of the air tube 19, may, if desired,

be conveniently varied either by axial adjustment of the tubular airconveyer 17 and its tube 19 in the bore 5 or the gas nozzle 12 on theboss 2 to obtain the most satisfactory results.

It is to be understood that the illustrations herein shown are as nearas practical drawn to scale but, for convenience of illustration, thetube 19 is somewhat exaggerated in its diameter and that in thecommercial device said tube is approximately one-half the diameter asthat depicted.

Heretofore, in the use of natural gas through commercially knownblowpipes it has been found difficult to prevent the flame beingextinguished by the slightest current of surrounding air. However, thishas been satisfactorily overcome by so forming the nozzle substantiallyflat at its outer end surface and conically inclined within so that itswalls are so related as to form an obtuse angle at the apex of a cone ifextended.

By such formation a condition obtains wherein a globular flame is formedat the base of the needle flame which prevents accidental extinguishmentof said needle flame and maintains it in an ignited condition.

I do not desire to limit my invention to the precise details ofconstruction and arrangement as herein set forth, as it is obvious thatvarious modifications may be made therein without departing from theessential features of my invention as defined in the appended claim.

Having thus described my invention, I claim:

A blowpipe comprising inlets for gas and air, a nozzle forming anelongated gas chamber and having a transverse forward end wall providedwith an outlet aperture and having its outer surface surrounding saidaperture substantially flat and its inner surface converging as thesurface of an obtuse angular truncated cone, causing the gas emittedfrom said chamber under pressure to assume a conical film formation, andan air conveyor extending through said chamber having an outlet apertureterminating at the apex of such conical film.

RUSSELL E. IRISH.

